1. Field of the Invention
The present invention relates to IQ mismatch compensation, and in particular relates to a transceiver capable of IQ mismatch compensation on the fly and a method thereof.
2. Description of the Related Art
Wireless communication devices are commonly deployed in wireless communication systems to provide communication services such as voice, multimedia, data, broadcast, and messaging services. In a conventional wireless communication device such as a mobile phone, a digital baseband circuit block provides a data stream of complex, digital baseband data to a transmitter, where the transmitted baseband data are often carried on an orthogonal transmitter signal represented by real components and imaginary components, or, in-phase (I) and quadrature (Q) components. In the transmitter, the real component and the imaginary component of the transmitter signal are processed along a real-component circuit path and the imaginary component is processed along an imaginary-component circuit path, parallel to each other. The digital and analog signal processing along the real-component and the imaginary-component circuit paths are all in parallel, and may include multiplexing, filtering, power control, and up-sampling processes, and so on. The parallel signal processed transmitter signal is modulated to produce an analog radio frequency (RF) signal to be amplified and radiated onto the air interface from an antenna, providing communication data exchange with a base station of the communication system.
Ideally, the real and imaginary components are processed along parallel circuit paths in the transmitter, and the circuit elements along one path are perfectly identical, or “matched”, with corresponding circuit elements along the other parallel channel. However, the corresponding circuit elements along the real and imaginary circuit paths often have slight or relatively significant differences from each other due to manufacturing process variations and geometrical layout differences, resulting in non-negligible amplitude differences (“IQ gain mismatch”) and phase differences (“IQ phase mismatch”) between the real and imaginary components that are processed along the parallel paths. The non-negligible IQ gain and phase mismatch may result in unacceptable degraded signal quality.
Typically, IQ mismatch compensation is deployed in the communication device to compensate for the IQ mismatch to increase the signal quality upon system startup or during a factory test. However, the system environment of the wireless communication device such as temperature changes during normal operation, lead to a change in the IQ mismatch in the device. Thus, devices capable of IQ mismatch compensation on the fly and methods thereof are in need, to accurately account for the IQ imbalance in the device when under normal operation.